1. Field of the Invention
This invention relates to devices for separating solid particles from fluid solutions and reducing the mass of the particles until they dissolve into solution.
2. Discussion of Related Art
In the manufacture of liquid fertilizer, it is necessary to cause dry fertilizer products such as phosphate, nitrogen, pot ash and lime to mix with and dissolve in water to produce the fertilizer. It is beneficial to reduce the size of the particles of dry fertilizer material in order to accelerate the dissolving of the solid materials.
Toward the end of reducing the size of chunks of fertilizer material, several systems have been suggested. For example, U.S. Pat. No. 1,739,732, issued Dec. 17, 1929, to Parrish, discloses a process wherein dry fertilizer material is passed through a series of screens having progressively smaller apertures. Associated with each screen is a crushing device which is especially adapted for handling material rejected by that screen. U.S. Pat. No. 3,532,276, issued Oct. 6, 1970, to Dunn, shows a drum screen for fertilizer wherein granular or particulate materials are fed into an upper end of a rotating drum mounted at an inclination to the horizontal. The drum is formed from a screen having progressively larger openings toward the lower end of the drum. Coarser particles flow down and through the coarser screen and into a device which comminutes the larger particles.
Systems which use cyclone separaters for classifying particles by size are also known. For instance, U.S. Pat. No. 3,543,932, issued Dec. 1, 1970, to Rastatter shows a separating device wherein paper pulp suspensions are fed to a plurality of parallel cyclone separators. The accepted stock is transferred to a holding tank while the rejected stock is fed to a common conduit. The conduit is connected to the input of a further cyclone separator with the accepted stock therefrom being returned to the original cyclone separators and the rejected stock therefrom being transferred to a waste receptacle. U.S. Pat. No. 3,794,251, issued Feb. 26, 1974, to Williams, shows an arrangement whereby a fluid bed of material is established in a mill by an air circulating blower creating a flow through a venturi of a velocity sufficient to suspend fines in the incoming material while allowing the larger and heavier particles to separate out and pass down through the venturi to be impacted by the mill hammers and forcibly returned through the venturi after being reduced in size. The particles suspended in the air flow are transported to a cyclone separator for removal in the usual manner so that substantially clean air is returned to the venturi.